title: Hemodynamics and myocardial blood flow patterns after placement of a cardiac passive restraint device in a model of dilated cardiomyopathy.
abstract: BACKGROUND
  The present study examined a cardiac passive restraint device which applies epicardial pressure (HeartNet Implant; Paracor Medical, Inc, Sunnyvale, Calif) in a clinically relevant model of dilated cardiomyopathy to determine effects on hemodynamic and myocardial blood flow patterns.
  
  
  METHODS
  Dilated cardiomyopatht was established in 10 pigs (3 weeks of atrial pacing, 240 beats/min). Hemodynamic parameters and regional left ventricular blood flow were measured under baseline conditions and after acute placement of the HeartNet Implant. Measurements were repeated after adenosine infusion, allowing maximal coronary vasodilation and coronary flow reserve to be determined.
  
  
  RESULTS
  Left ventricular dilation and systolic dysfunction occurred relative to baseline as measured by echocardiography. Left ventricular end-diastolic dimension increased and left ventricular fractional shortening decreased (3.8 ± 0.1 vs 6.1 ± 0.2 cm and 31.6% ± 0.5% vs 16.2% ± 2.1%, both P < .05, respectively), consistent with the dilated cardiomyopathy phenotype. The HeartNet Implant was successfully deployed without arrhythmias and a computed median mid-left ventricular epicardial pressure of 1.4 mm Hg was applied by the HeartNet Implant throughout the cardiac cycle. Acute HeartNet placement did not adversely affect steady state hemodynamics. With the HeartNet Implant in place, coronary reserve was significantly blunted.
  
  
  CONCLUSIONS
  In a large animal model of dilated cardiomyopathy, the cardiac passive restraint device did not appear to adversely affect basal resting myocardial blood flow. However, after acute HeartNet Implant placement, left ventricular maximal coronary reserve was blunted. These unique results suggest that cardiac passive restraint devices that apply epicardial transmural pressure can alter myocardial blood flow patterns in a model of dilated cardiomyopathy. Whether this blunting of coronary reserve holds clinical relevance with chronic passive restraint device placement remains unestablished.
authors.affiliation: Division of Cardiothoracic Surgery, Medical University of South Carolina and Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Dixon
authors.forename: Amy M
authors.initials: AM
authors.lastname: Goodman
authors.forename: William F
authors.initials: WF
authors.lastname: Gaillard
authors.forename: William T
authors.initials: WT
authors.lastname: Rivers
authors.forename: Richard A
authors.initials: RA
authors.lastname: McKinney
authors.forename: Rupak
authors.initials: R
authors.lastname: Mukherjee
authors.forename: Nathaniel L
authors.initials: NL
authors.lastname: Baker
authors.forename: John S
authors.initials: JS
authors.lastname: Ikonomidis
authors.forename: Francis G
authors.initials: FG
authors.lastname: Spinale
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D003326:Coronary Circulation; D004195:Disease Models, Animal; D006439:Hemodynamics; D008297:Male; D011474:Prosthesis Design; D019919:Prosthesis Implantation / Q000295:instrumentation*; D011651:Pulmonary Artery / Q000503:physiopathology; D012039:Regional Blood Flow; D013552:Swine; D013997:Time Factors; D014463:Ultrasonography; D014664:Vasodilation; D016277:Ventricular Function, Left; D017725:Ventricular Pressure